The present invention relates to a transformer, and more particularly, to a transformer with high coupling efficiency.
A chip coil transformer is an important device in the surface mounting technology and it is usually assembled on a circuit substrate to provide a variety of voltages for the circuit.
FIG. 1 illustrates the chip coil transformer 10 of the prior art. The prior chip coil transformer 10 includes a bobbin 12, low-voltage conducting wires 13, high-voltage conducting wires 14, and a core 15. A plurality of partitions 16 and pins 17 are disposed on the bobbin 12. A winding region 18 is formed between two of the partitions 16, and there are seven winding regions 18-24 formed on the bobbin 12 as shown in FIG. 1. Low-voltage conducting wires 13 are wound onto the winding region 18 to form a low-voltage winding loop. High-voltage conducting wires 14 are wound onto the winding region 19-24 to form a high-voltage winding loop. Each two of the winding regions 18-24 are isolated by means of each corresponding partition 16. Besides, each pin 17 functions as an output and an input for the low-voltage conducting wires 13 or the high-voltage conducting wires 14.
However, because the low-voltage conducting wires 13 and the high-voltage conducting wires 14 are wound onto the same bobbin 12, the coupling efficiency of the low-voltage winding loop and the high-voltage winding loop on the winding regions 18 and 24, which are at both ends of the bobbin 12, is not desirable. The length of the bobbin 12 is not easy to be reduced either. Moreover, each of the partitions 16 provided to isolate the winding regions 18-24 occupies a certain space, and therefore the industry faces a technical problem in minimizing the electronic parts.
To solve the above problem, the present invention provides a transformer with high coupling efficiency including a substrate, a bobbin, and a device. The substrate having M sets of pads and M sets of lower conducting wires is defined to have a front surface and a rear surface. Each set of pads includes a first pad and a second pad provided on the substrate acting as connecting point for the front surface and the rear surface of the substrate. Each set of the lower conducting wire is provided on the rear surface of the substrate to connect the first pad and the second pad of the corresponding set of pads. The bobbin is provided on the substrate functioning as a winding reel for a high-voltage conducting wire. The device having N sets of upper conducting wires is disposed on the bobbin. Each set of upper conducting wire connect the first pad of one set of pads with the second pad of another set of pads adjacent to the one set of pads. And these N sets of upper conducting wires connect respectively with the M sets of lower conducting wires by these M sets of pads to form a low-voltage winding loop on the device and the rear surface of the substrate. Because the low-voltage winding loop and the high-voltage winding loop of the present invention are located respectively on the device, the rear surface of the substrate, and the bobbin, the transformer of the present invention may have higher coupling efficiency. Besides, because there appears to be no partition formed on the bobbin, the transformer of the present invention is characterized by minimizing its volume.